This study demonstrated that the resting and dynamic visual analogue pains were comparable in the three study groups at 2 and 4 hours. Starting at 6 hours assessment point and over the 24 hour observation period, pain scores were significantly higher in the control group compared to other two groups.Preoperative serum magnesium levels were comparable in the three study groups. Intra-articular and intra-venous administration of magnesium was not associated with significant increase in serum magnesium levels compared to the control placebo group. Postoperative heart rate and arterial blood pressure changes adopted a similar pattern in the three study groups. At the 2 and 4 hours postoperative assessment points, heart rate and arterial blood pressure values were comparable.